1. Field of the Invention
The present invention relates to method and hub system for videoconferencing comprising:                a) a plurality of downlink ports, each adapted to be coupled to a communication channel to receive videoconferencing signals from participants, therefrom each signal comprising video- and audio streams as inputs and presenting the participants' images and their speaking, where one participant is the speaker in turn;        b) an uplink port, adapted to be coupled to a communication channel to transmit videoconferencing signal thereto, comprising a video stream in a frame and an audio stream as an output;        c) an engine adapted to process the inputs to the output for a distribution to the uplink port;        d) a controller coupled to said engine for providing control signals thereto and having means for a voice activity detection (VAD) for each communication channel;        e) thereby selectively controlling the processing and distribution of videoconferencing signals at said hub in accordance with the voice activity detection.        
The invention relates also to a terminal equipment for videoconferencing.
2. Description of the Prior Art
Video conferencing is used widely. Video calls are also used in 3G networks in cellular side. Voice activity detection (VAD) is used in speech coding systems.
Document WO 98/23075 discloses a hub for a multimedia multipoint video teleconferencing. It includes a plurality of input/output ports, each of which may be coupled to a communication channel for interchanging teleconferencing signals with remote sites. The hub has a plurality of signal processing functions that can be selectively applied to teleconferencing signals. Signal processing may include video, data, graphics and communication protocol or format conversion, and language translation. This system can handle multiple sites having incompatible communication standards.
Document EP 1178 683 discloses a multimedia attachment hub for a video conferencing system having a plurality of device ports that are physical ports for a plurality of multimedia devices and a terminal port that is a video conferencing terminal port providing a connection to a video conferencing terminal. This kind of system is applied when there are only two sites in videoconferencing.
The present systems select the video stream according to the voice activity detection. The video and audio streams of the speaker's communication channel are forwarded to other participants.
There remains a need for a system and a device that connects a plurality of participants in different sites and which also controls the video stream more user friendly. There is a need for a videoconferencing system enables the utilization of standard camera phones, particularly in video conference on top of 3G network.